DISSERTATION RESEARCH: Evolution of a novel phenotypes: The role of generalized enzyme function in adaptation

Duke University, Durham NC

Investigators

Abstract

Within a cell there are thousands of complex biochemical interactions, many of which are mediated by very specific enzymes. The evolution of complex biochemical interactions could follow a stepwise process, with each new elaboration of an enzyme being optimized by natural selection. However, very little is known about how these complex interactions have evolved and what evolutionary forces shape them. By examining the changing structures of an enzyme within the context of the phylogenetic tree of the organisms that have the different forms, one can trace the evolutionary history of a novel biochemical pathway and determine when a particular functional elaboration took place. Specifically, it is possible to use the variations in the present-day biochemical pathway to infer the DNA sequence underlying the extinct ancestral pathway. The DNA information can be used to infer the ancestral pathway and thus determine its function and understand how evolution acted on it to create the current pathway. Using plants of the family Brassicaceae (which includes crops like broccoli, cabbage, and canola), the PIs will examine the evolution of the biochemical pathway for forming a chemical that is crucial to deterring herbivores. This grant will also support the graduate student's outreach work at local elementary schools and the mentoring of 8th grade girls. International collaborations will be strengthened during this research. Finally, the anti-herbivore compounds made by this biochemical pathway are thought to play a role in cancer prevention, so the basic research described here could have medical as well as agricultural importance.